If Solved is enabled per-category, is there a way to quickly check all categories to see which ones it’s enabled on?
I don’t think this is possible through the UI, though you could pull this information out using a data explorer query. Something like this perhaps:
FROM category_custom_fields ccf
JOIN categories c ON c.id = ccf.category_id
WHERE ccf.name = 'enable_accepted_answers'
AND ccf.value = 'true'
ORDER BY c.position ASC